The Raman scattering of a molecule is generated by interactions of its electrons with incident light. The electric vector of the Raman scattered light is related to the electric vector of the incident light through a characteristic Raman tensor. A unique Raman tensor exists for each Raman-active molecular vibrational mode. In the case of biologically important macromolecules Raman tensors have been determined for a few hundred vibrational Raman bands. These include proteins and their amino acid constituents, as well as nucleic acids (DNA and RNA) and their nucleotide constituents. In this review Raman tensors for 39 representative vibrational Raman bands of biological molecules are considered. We present details of the Raman tensor determinations and discuss their application in structural studies of filamentous bacteriophages (fd, Pf1, Pf3 and PH75), fowl feather rachis and eyespots of the protists, Chlamydomonas and Euglena.

(Communicated by Saburo NAGAKURA, M.J.A.)

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In the past 20 years, rapid progress in stable isotope (SI) studies has allowed scientists to observe natural ecosystems from entirely new perspectives. This report addresses the fundamental concepts underlying the use of the SI ratio. The unique characteristics of the SI ratio make it an interdisciplinary parameter that acts as a chemical fingerprint of biogenic substances and provides a key to the world of isotopomers. Variations in SI ratios of biogenic substances depend on the isotopic compositions of reactants, the pathways and kinetic modes of reaction dynamics, and the physicochemical conditions. In fact, every biogenic material has its own isotopic composition, its “dynamic SI fingerprint”, which is governed by its function and position in the material flow. For example, the relative SI ratio in biota is determined by dietary lifestyle, e.g., the modes of drinking, eating, and excreting, and appears highly regular due to the physicochemical differences of isotopomers. Our primary goal here is to elucidate the general principals of isotope partitioning in major biophilic elements in molecules, biogenic materials, and ecosystems (Wada, E. et al., 1995). To this end, the nitrogen and carbon SI distribution ratios (δ¹⁵N and δ¹³C, respectively) are used to examine materials cycling, food web structures, and their variability in various kinds of watershed-including aquatic ecosystems to elucidate an “isotopically ordered world”.

(Communicated by Koichi TANAKA, M.J.A.)

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The complete nucleotide sequence of chloroplast DNA (121,025 base pairs, bp) from a liverwort, Marchantia polymorpha, has made clear the entire gene organization of the chloroplast genome. Quite a few genes encoding components of photosynthesis and protein synthesis machinery have been identified by comparative computer analysis. We also determined the complete nucleotide sequence of the liverwort mitochondrial DNA and deduced 96 possible genes in the sequence of 186,608 bp. The complete chloroplast genome encodes twenty introns (19 group II and 1 group I) in 18 different genes. One of the chloroplast group II introns separates a ribosomal protein gene in a trans-position. The mitochondrial genome contains thirty-two introns (25 group II and 7 group I) in the coding regions of 17 genes. From the evolutionary point of view, we describe the origin of organellar introns and give evidence for vertical and horizontal intron transfers and their intragenomic propagation. Furthermore, we describe the gene organization of the Y chromosome in the dioecious liverwort M. polymorpha, the first detailed view of a Y chromosome in a haploid organism. On the 10 megabase (Mb) Y chromosome, 64 genes are identified, 14 of which are detected only in the male genome. These 14 genes are expressed in reproductive organs but not in vegetative thalli, suggesting their participation in male reproductive functions. These findings indicate that the Y and X chromosomes share the same ancestral autosome and support the prediction that in a haploid organism essential genes on sex chromosomes are more likely to persist than in a diploid organism.

(Communicated by Yasuyuki YAMADA, M.J.A.)

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α-Klotho was first identified as the responsible gene in a mutant mouse line whose disruption results in a variety of premature aging-related phenotypes. α-Klotho has been shown to participate in the regulation of parathyroid hormone secretion and trans-epithelial transport of Ca²⁺ in the choroid plexus and kidney. α-Klotho, acting as a cofactor for FGF23, is also a major regulator of vitamin D biosynthesis and phosphate reabsorption in the kidney. These suggest that α-Klotho is a key player that integrates a multi-step regulatory system of calcium and phosphate homeostasis. Collectively, the molecular function of α-Klotho reveals a new paradigm that may change current concepts in mineral homeostasis and give rise to new insights in this field.

(Communicated by Takao SEKIYA, M.J.A.)

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